Rotary connector

ABSTRACT

A rotary connector ( 1 ) is provided having a stator housing ( 2 ) provided on a body of an automobile, a rotor housing ( 3 ) rotatably assembled to the stator housing ( 2 ) and coupled to a steering wheel ( 11 ), and a flat cable ( 5 ) accommodated in a space defined between the rotor housing ( 3 ) and the stator housing ( 2 ). The rotary connector ( 1 ) includes a rotor ( 8 ) having projections ( 8   a ). The stator housing ( 2 ) is formed with engagement portions ( 2   a ). The projections ( 8   a ) engage the engagement portions ( 2   a ) to prevent the rotor housing ( 3 ) from rotating. With this construction, the rotary connector can be rotatably locked during assembly even if a turn signal switch is not to be assembled under the steering wheel.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a rotary connector forelectrically connecting the body and the steering wheel of anautomobile, and more particularly to a rotary connector having a rotorhousing that can be locked to a stator housing.

[0003] 2. Description of the Related Art

[0004] A conventional rotary connector is disclosed, for example, inJapanese Utility Model Preliminary Publication (KOKAI) No. 1-83287. Thisconventional rotary connector is provided with a fastening means forfixing a rotor housing, the fastening means engaging a cancel cam sleeveof a turn signal switch such that the fastening means is movable inaxial directions of the cancel cam.

[0005] When the steering wheel of a vehicle is rotated, the rotaryconnector mounted on the vehicle is also allowed to rotate throughapproximately two rotations in each of a clockwise direction and acounterclockwise direction, from a neutral position of the steeringwheel at which the vehicle runs straight.

[0006] If this rotary connector is assembled to the vehicle at anoff-neutral position by mistake, the steering wheel cannot be rotatedthrough two rotations either clockwise or counterclockwise. Forciblyrotating the steering wheel causes the cutting off of the flat cableassembled inside the rotary connector. In order to prevent such anaccident, the prior art rotary connectors have a variety of fasteningmeans.

[0007] The fastening means disclosed in the aforementioned prior artdocument is constructed such that when a rotary connector is disposed onthe turn signal switch and the steering wheel has not been assembled onthe rotary connector, a projection of the rotary connector moves into acutout formed in a cancel cam of the turn signal switch to preventrotation of the rotary connector.

[0008] When the steering wheel has been assembled on the rotaryconnector, the cancel cam is pressed against the lower surface of thesteering wheel, so that the projection moves out of the cutout to allowthe cancel cam to rotate.

[0009] The prior art rotary connector and turn signal switch aremanufactured at separate plants and delivered separately to a finalassembly plant. The rotary connector is assembled on the turn signalswitch immediately before the steering wheel is assembled on the rotaryconnector.

[0010] However, the aforementioned prior art rotary connector suffersfrom the problem that after the turn signal switch has been disengagedfrom the rotary connector, the projection is out of the cutout and nolonger performs a locking function. Thus, the aforementioned prior artrotary connector does not have a locking function if the turn signalswitch is not to be assembled to the underside of the rotary connector.Accordingly, the prior art connector cannot be applied to a turn signalswitch of a cluster switch type in which the turn signal switch islocated beside an instrument panel.

[0011] Another type of locking means for a rotary connector is one inwhich a locking pin is inserted into both the rotor housing and thestator housing to prevent the rotor housing from rotating. With thistype of locking means, the locking pin is pulled out of the rotaryconnector and put aside once the rotary connector has been assembled tothe vehicle. Thus, it is uneconomical.

[0012] When the rotary connector is disengaged from the steering wheelfor the purposes of checking and repairing the steering wheel, the rotorhousing cannot be locked since the locking pin has been thrown away andthe rotary connector no longer has the locking pin accordingly. If therotor housing cannot be locked at a predetermined rotational position,the steering wheel may not be assembled properly.

[0013] As mentioned above, the rotary connector assembled in the wrongway is unable to rotate through two complete rotations either clockwiseor counterclockwise. Attempting to forcibly rotate the steering wheelwill cause the cutting off of the flat cable. The cutting of the flatcable leads to a drawback that an air bag, a horn, and the like providedon the steering wheel cannot operate properly.

SUMMARY OF THE INVENTION

[0014] An object of the present invention is to solve theabove-described problems of the prior art, and to provide a rotaryconnector that can be locked even if the turn signal is not to beassembled under the steering wheel.

[0015] The present invention provides a rotary connector having a statorhousing provided on a body of an automobile, a rotor housing that isrotatably assembled to the stator housing and is coupled to a steeringwheel, and a flat cable that is accommodated in a space defined betweenthe rotor housing and the stator housing. The rotary connector comprisesa rotor having a projection, and the stator housing is formed with anengagement portion. The projection engages the engagement portion toprevent the rotor housing from rotating.

[0016] The rotor comprises a cylinder inserted into a hollow shaftcylinder of the rotor housing. The projection is formed on acircumference of the cylinder. A pressing surface is formed on the rotorthat presses a lower surface of the steering wheel when the steeringwheel is assembled to the rotary connector.

[0017] The projection of the rotor is one of a plurality of projectionsthat project from a lower portion of the cylinder. The engagementportion of the stator housing is a projection that projects from abottom surface of the stator housing.

[0018] The rotor is assembled to an attachment that couples the statorhousing and the rotor housing together such that the rotor housing isrotatable relative to the stator housing. The attachment supports aspring that urges the rotor. The spring has an upper end in pressurecontact with the projections and a lower end received between an annulargroove formed in the attachment and a projection formed on an inner sideof the annular groove.

[0019] The rotor and annular groove are formed such that when thesteering wheel has been assembled on the rotary connector and the rotoris pushed down by the steering wheel, the projections of the rotor lowerinto the annular groove. The attachment has vertical grooves into whichthe projections enter such that the projections are vertically movablein the vertical grooves.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention will become more clearly appreciated as thedisclosure of the invention is made with reference to the accompanyingdrawings. In the drawings:

[0021]FIG. 1 is a partial cross-sectional side view of an embodiment ofthe invention, illustrating a steering wheel mounted to the rotaryconnector.

[0022]FIG. 2 is a partial cross-sectional side view of the embodiment ofthe invention, illustrating the steering wheel before it is mounted tothe rotary connector.

[0023]FIG. 3 is an enlarged partial cross-sectional side view of theembodiment of the invention, illustrating the steering wheel before itis mounted to the rotary connector.

[0024]FIG. 4 illustrates the embodiment of the invention, showing anexploded perspective view of a pertinent portion.

[0025]FIG. 5 illustrates the embodiment of the invention and is a bottomview of the engagement portions formed on the bottom surface of thestator housing.

DETAILED DESCRIPTION OF THE INVENTION

[0026] A rotary connector 1 according to a preferred embodiment of thepresent invention will now be described in detail with reference toFIGS. 1 to 5 of the drawings.

[0027] The rotary connector 1 electrically connects between a steeringwheel 11 and a body of an automobile. The rotary connector 1 includes: astator housing 2 mounted on a combination switch (not shown) that isfixedly mounted to a steering column (not shown); a rotor housing 3 thatis fastened to the underside of the steering wheel 11 and rotatestogether with the steering wheel 11; an attachment 4 on which the rotorhousing 3 is rotatably supported; a flat cable 5 accommodated in a spacedefined between the stator housing 2 and the rotor housing 3, the flatcable forming, for example, a spiral; a rotor 8 assembled between thestator housing 2 and the attachment 4; and a spring 9 that urges therotor 8 upwardly.

[0028] The stator housing 2 is a stationary structure that is fixed bymeans of, for example, screws onto a base (not shown) of the combinationswitch. The stator housing 2 has engagement portions 2 a formed on itsbottom surface, the engagement portions 2 a being engaged withlater-described projections 8 a of the rotor 8. The stator housing 2includes a side housing 6 and a bottom housing 7, which are assembled toeach other. In more detail, the side housing 6 has a fitting hole (notshown), and the bottom housing 7 has a fitting claw (not shown). Theside housing 6 and the bottom housing 7 are assembled together with thefitting claw fitted into the fitting hole.

[0029] The side housing 6 and bottom housing 7 may be formed in onepiece construction as the stator housing 2. The engagement portions 2 amay be in the form of a projection, a recess, or any shape, providedthat the engagement portions 2 a can engage generally rod-shapedprojections 8 a.

[0030] As shown in FIG. 1, the bottom housing 7 supports an end of theflat cable 5 and has a guide (not shown) that guides the flat cable 5 inthe space defined between the stator housing and the rotor housing 3.The bottom housing 7 has a slide sheet 13 placed on the bottom of thespace. The side housing 6 has a connector 6 a disposed below the guide.

[0031] The connector 6 a has terminals (not shown) which are connectedvia the flat cable 5 to a wire harness 10 disposed on the rotor housing3. The slide sheet 13 is a flat ring formed of oleoresin and allows theflat cable 5 to smoothly slide, thereby reducing the noise when the flatcable 5 slides on the bottom floor of the space.

[0032] The side housing 6 includes a generally ring-shaped cylinder 6 band a frame 6 c that is formed to surround the lower portion of thecylinder 6 b. The cylinder 6 b and frame 6 a are formed in one piececonstruction. The frame 6 c is formed with the connector 6 a thereon,and a threaded hole therein through which the rotary connector 1 isscrewed into the base of the combination switch. As shown in FIG. 5, theside housing 6 and the rotor housing 3 have a mark 3 g and a mark 6 d,respectively, formed thereon, such that when the marks 3 g and 6 d faceeach other, they indicate that the rotary connector is at the neutralposition of the wound flat cable.

[0033] With the coupling pin 12 engaging the lower surface of thesteering wheel 11, the rotor housing 3 rotatably fits to the statorhousing 2 and rotates together with the steering wheel 11. The rotorhousing 3 has claws 3 d formed in its inner circumferential surface 3 c,the claws 3 d engaging fitting portions 4 a provided in the attachment4. The rotor housing 3 also has a stepped portion (not shown) that abutsupright circumferential walls 4 b of the attachment 4.

[0034] The fitting portions 4 a and upright circumferential walls 4 b ofthe attachment 4, as shown in FIGS. 3 and 4, permit the stator housing 2to couple with the rotor housing 3. The attachment 4 has a flange 4 c atits lower circumference. That is, the attachment 4 couples with thestator housing 2 and rotor housing 3 by using a means disclosed in forexample, Japanese Patent Preliminary Publication (KOKAI) No. 10-22029.The flange 4 c includes an annular groove 4 d that receives a spring 9therein, an annular projection 4 e formed in the annular groove 4 d, anda supporting frame 4 f formed to surround the annular groove 4 d.

[0035] The lower end of the spring 9 is received between the annulargroove 4 d and the annular projection 4 e such that the spring 9 isprevented from moving laterally. The frame 4 f has a narrow ring-shapedgroove 4 g formed in the top surface 4 h of the frame 4 f. The topsurface 4 h abuts the bottom surface 2 b of the stator housing 2. Thering groove 4 g is a groove that holds a lubricant and a grease therein.The lubricant and grease are applied to the sliding surfaces of therotating attachment 4 and the bottom housing 7.

[0036] As shown in FIG. 4, the spring 9 is in the form of a compressedcoil spring. As shown in FIGS. 1 and 2, the lower end of the spring isreceived in the annular groove 4 d, and the upper end of the spring 9 isin pressure contact with the projections 8 a of the rotor 8.

[0037] The flat cable 5 includes, for example, a plurality ofbelt-shaped electrically conductive wires spaced apart by predeterminedintervals, the wires being sandwiched by two sheets of insulating resinfilm heat-bonded to each other. The flat cable 5 has one end thereofconnected to the terminals of the connector 6 a of the stator housing 2,and the other end thereof connected to the wire harness 10 of the rotorhousing 3.

[0038] The flat cable 5 is accommodated in the doughnut-shaped spacedefined by the stator housing 2 and the rotor housing 3 such that therotor housing 3 can be rotated through more than two rotations in eachof a clockwise direction and a counterclockwise direction from theneutral position at which the vehicle runs straight.

[0039] When the steering wheel 11 has not been mounted on the rotaryconnector 1, the rotor 8 causes the rotor housing 3 to engage the statorhousing 2, thereby preventing the rotor housing 3 from rotating. Therotor 8 includes a cylinder 8 b and the plurality of projections 8 a.The cylinder 8 b is disposed in a hollow shaft cylinder 3 f of the rotorhousing 3. The plurality of projections 8 a are provided at the lowerend of the cylinder 8 b and inserted into vertical grooves 4 i formed inthe attachment 4.

[0040] As shown in FIG. 5, the projections 8 a include four rod-likemembers. The projections 8 a may be of any number and any shape,provided that the projections 8 a can support the spring 9 and engagethe engagement portions 2 a.

[0041] In order to prevent fracture and the cutting-off of theprojections 8 a, the projections 8 a may have thick base portions orribs and may be in the shape of a tooth or wedge. The projections 8 aneed not be as many as the engagement portions 2 a and may differ innumber from the engagement portions 2 a. The number of projections 8 aand engagement portions 2 a may be increased or the shape of them may betriangular so that when the projections 8 a are engaged with theengagement portions 2 a, the projections 8 a and engagement portions 2 aare prevented from moving laterally, thus rattling can be reduced.

[0042] Because the projections 8 a enter the vertical grooves 4 i suchthat the projections 8 a are movable vertically in the vertical grooves4 i of the attachment 4, the rotor 8 rotates together with theattachment 4 and the rotor housing 3. The rotor 8 has a pressing surface8 c formed on the upper end of the cylinder 8 b, the pressing surface 8c abutting the lower surface 11 a of the steering wheel 11.

[0043] When the projections 8 a of the rotor 8 are in the verticalgrooves 4 i of the attachment 4, and the steering wheel 11 has not beenassembled on the rotary connector 1 yet, the spring 9 pushes up therotor 8 so that the projections 8 a engage the engagement portions 2 aon the bottom surface 2 b of the stator housing 2 and do not rotate asshown in FIG. 2.

[0044] When the steering wheel 11 has been assembled on the rotaryconnector 1, the pressing surface 8 c of the rotor 8 is pressed againstthe lower surface 11 a of the steering wheel 11 as shown in FIG. 1, sothat the projections 8 a are lowered while compressing the spring 9.Thus, the projections 8 a are disengaged from the bottom surface 2 b ofthe stator housing 2. The lowered projections 8 a enter the annulargrooves 4 d as shown in FIG. 1. Due to the disengagement of theprojections 8 a of the rotor 8 from the stator housing 2, the rotor 8,attachment 4, and rotor housing 3 become free to rotate relative to thestator housing 2.

[0045] The operation of the embodiment of the invention of theaforementioned construction will now be described. The rotor 8 isrotatable together with the rotor housing 3 and the attachment 4 at alltimes. The stator housing 2 is screwed to, for example, the base of thecombination switch. When the rotary connector 11 has not been mounted tothe lower surface 11 a of the steering wheel 11 yet, as shown in FIG. 2,the projections 8 a of the rotor 8 engage the engagement portions 2 aformed on the bottom surface 2 b of the stator housing 2 such that therotary connector is locked. Therefore, the rotor 8, rotor housing 3 andattachment 4 are fixed to the stator housing 2 and do not rotate.

[0046] When the steering wheel 11 is assembled on the rotary connector1, the pressing surface 8 c is pressed against the lower surface 11 a ofthe steering wheel 11, so that the projections 8 a disengage from theengagement portions 2 a of the stator housing 2. Thus, the rotor 8,rotor housing 3, and attachment 4 become free to rotate relative to thestator housing 2.

[0047] When the steering wheel 11 on the rotary connector 1 isdisengaged from the steering shaft, for example, for the purpose ofchecking or maintenance of the steering wheel 11, the steering wheelthat was depressing the rotor 8 is removed, so that the spring 9 pushesup the rotor 8. Then, the projections 8 a are raised to engage theengagement portions 2 a of the stator housing 2, thereby preventing therotor 8, rotor housing 3, and attachment 4 from rotating.

[0048] Therefore, even when the steering wheel 11 has not been assembledyet or the rotary connector 1 is stored as a single assembly, the rotorhousing 3 may be locked in position.

[0049] The rotary connector 1 incorporates the rotor 8 that serves as alocking mechanism. Thus, when the steering wheel 11 is disassembled fromthe vehicle for checking and maintenance purposes, the projections 8 aare allowed to engage the engagement portions 2 a, thereby maintainingthe positional relation between the projections 8 a and the engagementportions 2 a immediately before the steering wheel 11 has beendisengaged from the vehicle.

[0050] When the rotary connector 1 is replaced to the vehicle, the rotorhousing is not subjected to a large positional error. This prevents therotary connector from being assembled at a non-neutral position of thesteering wheel by mistake.

[0051] The present invention of the aforementioned construction providesthe following advantages.

[0052] The invention is a rotary connector having a stator housingprovided on a body of an automobile, a rotor housing that is rotatablyassembled to the stator housing and is coupled to a steering wheel, anda flat cable that is accommodated in a space defined between the rotorhousing and the stator housing. The rotor has a projection that engagesthe engagement portions formed on the stator housing to prevent therotor housing from rotating.

[0053] Thus, the present invention eliminates a conventional lockingmember that is inserted to extend through the rotor housing and thestator housing to lock the two housings relative to each other, and isthrown away after the rotary connector has been mounted to the steeringwheel. The present invention is useful because it provides easyrelocking of the rotor housing and the stator housing. Further, thelocking mechanism for locking the rotor housing to the stator housingremains assembled in the rotary connector. This locking mechanismprevents the rotation of the rotor housing and holds the rotor housingat a predetermined position relative to the stator housing even when thesteering wheel is dismounted from the vehicle after the steering wheelhas been mounted to the vehicle. The invention prevents the rotaryconnector from being misassembled when, for example, the checking andmaintenance of the steering wheel is performed.

[0054] The invention is further defined by the rotor comprising acylinder inserted into a shaft hollow cylinder of the rotor housing; theprojection formed on a circumference of the cylinder; and a pressingsurface that presses a lower surface of the steering wheel when thesteering wheel has been assembled to the rotary connector. Thus, whenthe steering wheel is assembled to the rotary connector, the rotor isoperatively lowered, so that the rotor housing is automaticallyunlocked.

[0055] The invention is further defined by the projection of the rotorbeing one of a plurality of projections that project from a lowerportion of the cylinder, and the engagement portion of the statorhousing is a projection that projects from a bottom surface of thestator housing. Thus, a simple structure permits the rotor housing to beengaged with and disengaged from the stator housing.

[0056] The invention is further defined by the rotor being assembled toan attachment that couples the stator housing and the rotor housingtogether such that the rotor housing is rotatable relative to the statorhousing; wherein the attachment supports a spring that urges the rotor.This provides a simple structure that permits the rotor to lower andraise operatively when the steering wheel is mounted to and dismountedfrom the rotary connector.

[0057] The invention is further defined by the spring having an upperend in pressure contact with the projections, and a lower end receivedbetween an annular groove formed in the attachment and a projectionformed on an inner side of the annular groove. The spring can besupported without buckling, thereby allowing the rotor to smoothly moveup and down.

[0058] According to another feature of the invention, when the steeringwheel has been assembled on the rotary connector and the rotor is pusheddown by the steering wheel, the projections of the rotor lower into theannular groove. This structure provides a shorter vertical dimension anda thinner overall thickness of the rotary connector.

[0059] The invention is further defined by the attachment havingvertical grooves into which the projections of the rotor enter such thatthe projections are vertically movable in the vertical grooves. Thissimple structure allows the rotor to be assembled such that the rotorinterlocks the attachment and the rotor housing at all times.

[0060] It will be appreciated that the present invention is not limitedto the exact constructions that have been described above andillustrated in the accompanying drawings, and that various modificationsand changes can be made without departing from the scope and spirit ofthe invention. It is intended that the scope of the invention only belimited by the appended claims.

What is claimed is:
 1. A rotary connector (1) comprising: a statorhousing (2) provided on a body of an automobile, the stator housingbeing formed with an engagement portion (2 a); a rotor housing (3)rotatably assembled to the stator housing (2) and coupled to a steeringwheel (11); a flat cable (5) accommodated in a space defined between therotor housing (3) and the stator housing (2); and a rotor (8) having aprojection (8 a) that engages the engagement portion (2 a) to preventthe rotor housing (3) from rotating.
 2. The rotary connector accordingto claim 1 , wherein the rotor (8) comprises: a cylinder (8 b) insertedinto a hollow shaft cylinder (3 f) of the rotor housing (3); theprojection (8 a) being formed on a circumference of the cylinder (8 b);and a pressing surface (8 c) that presses a lower surface (11 a) of thesteering wheel (11) when the steering wheel (11) has been assembled tothe rotary connector (1).
 3. The rotary connector according to claim 2 ,wherein the projection (8 a) of the rotor (8) is one of a plurality ofprojections that project from a lower portion of the cylinder (8 b), andthe engagement portion (2 a) of the stator housing (2) is a projectionthat projects from a bottom surface (2 b) of the stator housing (2). 4.The rotary connector according to claim 3 , wherein the rotor (8) isassembled to an attachment (4) that couples the stator housing (2) andthe rotor housing (3) together such that the rotor housing (3) isrotatable relative to the stator housing (3); wherein the attachment (4)supports a spring (9) that urges the rotor (8).
 5. The rotary connectoraccording to claim 4 , wherein the spring (9) has an upper end inpressure contact with the projections (8 a) and a lower end receivedbetween an annular groove (4 d) formed in the attachment (4) and aprojection (4 e) formed on an inner side of the annular groove (4 d). 6.The rotary connector according to claim 5 , wherein when the steeringwheel (11) has been assembled on the rotary connector (1) and the rotor(8) is pushed down by the steering wheel (11), the projections (8 a) ofthe rotor (8) lower into the annular groove (4 d).
 7. The rotaryconnector according to claim 5 , wherein the attachment (4) has verticalgrooves (4 i) into which the projections (8 a) of the rotor (8) entersuch that the projections (8 a) are vertically movable in the verticalgrooves (4 i).
 8. The rotary connector according to claim 4 , whereinthe attachment (4) has vertical grooves (4 i) into which the projections(8 a) of the rotor (8) enter such that the projections (8 a) arevertically movable in the vertical grooves (4 i).
 9. A rotary connectorfor providing an electrical connection between an automotive steeringwheel and a vehicle body, the rotary connector comprising: a statorhousing having an engagement portion that projects from a bottom surfaceof the stator housing; a rotor housing rotatably assembled to the statorhousing and adapted to be coupled to a steering wheel; an attachmentthat couples the stator housing and the rotor housing together such thatthe rotor housing is rotatable relative to the stator housing; a flatcable accommodated in a space defined between the rotor housing and thestator housing; and a rotor having a cylinder and a projection extendingoutwardly from a circumference of the cylinder, said rotor being movablealong an axis of rotation of the rotor housing between a first positionin which the projection engages the engagement portion and preventsrotation of the rotor housing, and a second position in which theprojection does not engage the engagement portion and allows rotation ofthe rotor housing.
 10. The rotary connector according to claim 9 ,wherein the projection of the rotor is one of a plurality of projectionsthat project from a lower portion of the cylinder.
 11. The rotaryconnector according to claim 10 , wherein the attachment supports aspring that urges the rotor.
 12. The rotary connector according to claim11 , wherein the spring has an upper end in pressure contact with theprojections and a lower end received between an annular groove formed inthe attachment and a projection formed on an inner side of the annulargroove.
 13. The rotary connector according to claim 12 , wherein saidrotor is movable to said second position upon assembling a steeringwheel on the rotary connector and pushing the rotor down by the steeringwheel, whereby the projections of the rotor lower into the annulargroove.
 14. The rotary connector according to claim 13 , wherein theattachment has vertical grooves into which the projections of the rotorenter such that the projections are vertically movable in the verticalgrooves.